Fluidic control apparatus

ABSTRACT

An air-drying arrangement with fluidic apparatus for controlling the cyclic operation of the device and powered from the air line rather than from any auxiliary electrical or other source, and the fluidic apparatus itself.

United States Patent inventors Appl. No.

Filed Patented Assignee Neil C. Sher;

John M. Zabsky, Minneapolis, Minn.

References Cited UNITED STATES PATENTS 10/1966 Freeman 6/1968 Bjornsen10/ 1 968 Shiiki 11/1968 Van Der Heyden et 211.. 3,459,206 8/1969 Dexter3,460,554 8/1969 Johnson Primary Examiner-Samuel Scott 137/815X 235/201X137/815 137/815X 137/815 137/815X Attorneys-Charles J. Ungemach, RonaldT. Reiling and FLUIDIC CONTROL APPARATUS G w l 6 Claims, 3 Drawing Figs.eorge re d Int. Cl FlSc 3/00 ABSTRACT: An air-drying arrangement withfluidic ap- Field of Search 137/815; paratus for controlling the cyclicoperation of the device and 235/20l(p.f.), (sens.)(gen.), 200(ana1.), ge n.),

powered from the air line rather than from any auxiliary elec- (p.f.}trical or other source, and the fluidic apparatus itself.

FROM COMPRESSOR flo as K PATENIED FEB 9 IBYI WW! I COMPRESSOR FIG. 5

INVENTORS NEH. C. SHER JOHN M.

MWRMEY FLUIDIC CONTROL APPARATUS BACKGROUND OF THE INVENTION Thisinvention relates to the fields of air-drying equipment and fluidiccontrol apparatus. Drying equipment is commercially available in which apair of desiccant cylinders are used alternately to dry air passingtherethrough, a portion of the dried air being thereafter used to purgethe desiccant in each cylinder while the other is being used'to dry theair. Known apparatus of this sort requires, however, the presence ofelectrically energized means for causing it to continually perform itscycle of operation.

SUMMARY OF THE INVENTION The present invention comprises a system asgenerally described above, in which the control means is fluidicallypowered from the air line itself, making it independent of any auxiliaryelectrical or other power source: the fluidic control means per se isalso a feature of the invention.

BRIEF DESCRIPTION OFTI-IE DRAWING Various objects, advantages andfeatures of novelty which characterize our invention are pointed outwith particularity in the claims annexed hereto and forming a parthereof. However, for a better understanding of the invention, itsadvantages, and objects attained by its used, reference should be had tothe drawing which forms a part hereof, and to the accompanyingdescriptive matter, in which we have illustrated and described apreferred embodiment of our invention.

In the drawing, FIG. 1 is a mechanical schematic showing the completesystem and the control subcomponent, and FIG. 2 and FIG. 3 areconceptual showings 'of structures useful in the system of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Our invention is shown in FIG. 1to fluidically a conduit connected to a pair of fluidically actuablevalves or relays 11 and 12. Valve 11 normally provides afirst flow pathbetween a first connection 13 and a second connection 14, but may befluidically energized at a connection 15 to interrupt the first path andestablish a second flow path between connection 14 and a furtherconnection 16 which vents to a fluid sink 17, in this case theatmosphere. Valve 12 normally provides a first flow path between a firstconnection 20 and a second connection 21, but maybe fluidicallyenergized at a connection 22 to interrupt the first path and establish asecond flow path between connection 21 and a further connection 23 whichvents to the atmosphere. Conduit 10 is joined to connection 13 of valve11 and connection 20 of valve 12.

Connection 14 of valve 11 is joined to one connection 24 o a chamber 25having a second connection 26 and filled with a suitable desiccant sothat any air passing between connections 24 and 26 must traverse the bedof desiccant. Connection 21 of valve 12 is joined to one connection 27of a chamber 30 having a second connection 31 and filled with thedesiccant, so that any air passing between connections 27 and 31 musttraverse the bed of desiccant.

Connection 26 of cylinder 25 is joined to a dry air conduit 32 through acheck valve 33 which permits flow only from the tank to the conduit.Similarly, connection 31 of cylinder 30 is joined to dry air conduit 32through a check valve 34 which permits flow only from the tank to theconduit.

Check valve 33 is bypassed by a restriction or calibrated orifice 35,and check valve 34 is bypassed by a similar restriction 36.

Connected to conduit 32 is the power nozzle 40 of a fiuid amplifier 41having a pair of control ports 42 and 43 and apair of outlet ports 44arid 45. Port 43 is connected to power nozzle 40 through a restriction46 so that the amplifier is biased to supply its output through outletport 44. Outlet port 45 is joined to control connection 22 of valve 12.Outlet port 44 is joined to control connection 15 of valve 11, and tothe control connection 47 of a further fluidically actuated valve orrelay 48 which normally provides a first flow path between a secondconnection 50 and a third connection 51, vented to the atmosphere,through a restriction 49, but which may be energized to interrupt thefirst flow path and establish a second flow path between connection 50and a further connection 52, including a restriction 53, which is joinedto conduit 32.

Connection 50 is joined to a fluid capacitor or tank 54, which isfurther joined through a variable restriction to control port 42 offluid amplifier 41.

FIG. 2 shows conceptually a structure usable for valve 12: the samevalve structure is equally suitable for valve 11. A chamber contains alongitudinally moveable piston 61 normally urged to the left as seen inFIG. 2 by a compression spring 62. Connections 20, 21, 22 and 23 piercethe chamber wall: in the normal condition of the: valve a first,transverse bore 63 in piston 61 prdvides a flow path between connections20 and 21. When air flows into connection 22, piston 61 is displaced tothe right, compressing spring 62. This displaces bore 63 to the right,interrupting the original flow path, and a second bore 64 is broughtinto alignment with connection 21: bore 64 opens at the end of thepiston to communicate with connection 23.

FIG. 3 shows conceptually a structure usable for valve 48, which isgenerally like that just described. Here a cylinder contains apiston'7l, having bores 72 and 73, and a compression spring 74. Normallythe piston is positioned so that bore 72 completes a first flow pathbetween connecting 50 and connection 51. When air flows into connection47, piston 71 is displaced downwardly, compressing spring 74. Thisdisplaces bore 72 to interrupt the first flow path, and'bore 73 isbrought into alignment with connection 50, thus completing a second flowpath from connection 50 to connection 52.

The operation of our invention is as follows. When the system compressoris started, pressure rises in conduit 10 and air flows to conduit 32through valve II, the desiccant in chamber 25, and check valve 33 andthrough valve 12, the desiccant in chamber 30, and check valve 34, beingdried in the process. As the pressure in conduit 32 increases, fluidflows into the power nozzle 40 of amplifier 41 and also throughrestriction 46 to control port 43, thus establishing flow out of theamplifier through port 44. At this time, tank 54 is vented to theatmosphere through valve 48 and hence is at atmospheric pressure.

When the fluidic signal from output port 44 becomes sufficiently large,valve 11 is actuated to cut off chamber 25 from conduit 10 and toconnect the chamber to vent 16. Dry air from conduit 32 may now flowthrough chamber 25 to dry the desiccant, but the rate of flow is limitedby restriction 35 because check valve 33 closes: the pressure in chamber25 is substantially that of the atmosphere: 17. The path from conduit 10through chamber 30 to conduit 32 is not altered, so pressure in conduit32 is maintained, at a level somewhat less than that in conduit 10.Chamber 30 is doing the drying and chamber 25 is being purged at thistime.

The signal from outlet port 44 also acts, when it becomes sufficientlylarge, to actuate valve 48, interrupting the vent path from tank 54 andconnecting, the tank to conduit 32 through restriction 53. Tank 54 thensupplies a gradually in creasing signal through restriction 55 tocontrol port 42: when this signal becomes sufficiently larger than thatin port 43, the amplifier switches, transferring its output from port 44to port 45. Valve 11 now returns to its initial condition, interruptingthe vent path for dry air through chamber 25 and reestablishing the pathto the chamber from conduit 10. At the same time, valve 12 is actuatedto interrupt the path from conduit 10 to conduit 32 and substitute thepath from chamber 30 to vent 23. Now chamber 25 is doing the drying andchamber 30 is being purged.

Switching of the amplifier also allows valve 48 to return to its initialstate, in which tank 54 is cut off from conduit 32 and allowed to ventthrough restriction 49 as well as through restriction 55, the latterflow path being continuous. The

signal to control port 42 now decreases slowly to a point whereamplifier 22 again switches, and the system continues to operate in thecycle described, first one chamber and then the other being purged,while the alternate chambers are performing the drying function.Restriction 53 is so adjusted, having regard for the mean pressures inconduit 32 and tank 54, that the time required to increase the signal atcontrol port 42 to a level sufficient to switch amplifier 41 is the sameas that required for the signal to decrease to a point where theamplifier switches back. The difference between these two signals atcontrol port 42 is the hysteresis of the amplifier, upon which operationof the control system is based.

lt will be appreciated that the control system including fluid amplifier41 and valve 48 could be energized from conduit if desired, rather thanfrom conduit 32.

Numerous objects and advantages of our invention have been set forth inthe foregoing description, together with details of the structure andfunction of the invention, and the novel features thereof are pointedout in the appended claims. The disclosure, however, is illustrativeonly, and we may make changes in detail, especially in matters ofshape', size and arrangement of parts, within the principle of theinvention, to the full extent indicated by the broad general meaning ofthe terms in which the appended claims are expressed.

We claim:

i. Apparatus of the class described comprising in combination:

first and second fluid manifolds;

first and second chambers each having first and second connections fordirected fluid flow therethrough',

means continuously connecting said first manifold to said firstconnections for substantially free flow of fluid out of said chambersand for restricted flow of fluid into said chambers;

first and second valve means connected between said second manifold andsaid second connections and severally having first conditions, providingflow paths from said second manifold to said second connections, andsecond conditions, interrupting said flow paths and substituting flowpaths for free discharge of fluid from said second connection; and

fluid actuated means connected to said valve means and to one of saidmanifolds for cyclically causing simultaneous opposite conditions ofsaid valve means followed by reversed simultaneous opposite conditionsof said valve means.

2. Apparatus according to claim 1 in which the fluid-actuated meanscomprises hysteretic fluidic switching means, means normally biasingsaid switching means in a first position, and time element means forcyclically varying a fluid input to said switching means through a rangegreater than the hysteresis thereof.

3. Apparatus according to claim 2 in which the time element meanscomprises a fluidic capacitor and means connecting said capacitoralternately to a fluid source and to a fluid sink.

4. Apparatus according to claim 3 in which the last named means isconnected to the switching means for triggering thereby to cause thealternate operation.

5. In combination: hysteretic fluidic control means for giving first andsecond outputs respectively according as a variable fluid input theretois of greater or less than a predetermined magnitude; fluid energystorage means; means providing a flow path, having a first impedance,between said storage means and said first control means; a fluid source;a fluid sink; I further fluid-actuated means having, first, second, andthird fluid connections and operable out of a normal first ,condition,in which a flow path is established between said first and thirdconnections, and into a second condition in wh|ch a flow path isestablished between said first an second connections, said second andthird connections providing flow paths to said source and said sinkrespectively; means providing a further flow path having a secondimpedance, less than said first impedance, between said storage meansand said first connection; and means interconnecting said" control meansso that said further control means is operated into said secondcondition by the first output of said first control means. 6. Apparatusof the class described comprising in combination:

first and second fluid manifolds; first and second chambers each havingfirst and second connections for directed fluid flow therethrough; meanscontinuously connecting said first manifold to said first connectionsfor substantially free flow of fluid out of said chambers and forrestricted flow of fluid into said chambers; valve means connectedbetween said second manifold and said second connections, and having afirst condition, providing a flow path from said second manifold to afirst of said second connections and a flow path for free discharge offluid from a second of said second connections, and a second condition,providing a flow path from said second manifold to said second of saidsecond connections and a flow path for free discharge of fluid from saidfirst of said second connections; and fluid-actuated means connected tosaid valve means and to one of said manifolds for cyclically causingsaid valve means to alternate between said first and second conditions.

1. Apparatus of the class described comprising in combination: first andsecond fluid manifolds; first and second chambers each having first andsecond connections for directed fluid flow therethrough; meanscontinuously connecting said first manifold to said first connectionsfor substantially free flow of fluid out of said chambers and forrestricted flow of fluid into said chambers; first and second valvemeans connected between said second manifold and said second connectionsand severally having first conditions, providing flow paths from saidsecond manifold to said second connections, and second conditions,interrupting said flow paths and substituting flow paths for freedischarge of fluid from said second connection; and fluid actuated meansconnected to said valve means and to one of said manifolds forcyclically causing simultaneous opposite conditions of said valve meansfollowed by reversed simultaneous opposite conditions of said valvemeans.
 2. Apparatus according to claim 1 in which the fluid-actuatedmeans comprises hysteretic fluidic switching means, means normallybiasing said switching means in a first position, and time element meansfor cyclically varying a fluid input to said switching means through arange greater than the hysteresis thereof.
 3. Apparatus according toclaim 2 in which the time element means comprises a fluidic capacitorand means connecting said capacitor alternately to a fluid source and toa fluid sink.
 4. Apparatus according to claim 3 in which the last namedmeans is connected to the switchinG means for triggering thereby tocause the alternate operation.
 5. In combination: hysteretic fluidiccontrol means for giving first and second outputs respectively accordingas a variable fluid input thereto is of greater or less than apredetermined magnitude; fluid energy storage means; means providing aflow path, having a first impedance, between said storage means and saidfirst control means; a fluid source; a fluid sink; furtherfluid-actuated means having first, second, and third fluid connectionsand operable out of a normal first condition, in which a flow path isestablished between said first and third connections, and into a secondcondition, in which a flow path is established between said first andsecond connections, said second and third connections providing flowpaths to said source and said sink respectively; means providing afurther flow path having a second impedance, less than said firstimpedance, between said storage means and said first connection; andmeans interconnecting said control means so that said further controlmeans is operated into said second condition by the first output of saidfirst control means.
 6. Apparatus of the class described comprising incombination: first and second fluid manifolds; first and second chamberseach having first and second connections for directed fluid flowtherethrough; means continuously connecting said first manifold to saidfirst connections for substantially free flow of fluid out of saidchambers and for restricted flow of fluid into said chambers; valvemeans connected between said second manifold and said secondconnections, and having a first condition, providing a flow path fromsaid second manifold to a first of said second connections and a flowpath for free discharge of fluid from a second of said secondconnections, and a second condition, providing a flow path from saidsecond manifold to said second of said second connections and a flowpath for free discharge of fluid from said first of said secondconnections; and fluid-actuated means connected to said valve means andto one of said manifolds for cyclically causing said valve means toalternate between said first and second conditions.